Method of handling gas



3,217,503 Patented Nov. 116, 1965 Flee 3,217,503 METHOD 6F HANDHNG GAS William A. Mitchell, Lincoln Park, Nl, Harry N flames, Valley Cottage, N.Y., and Leon T. Krenrzner, Upper Saddle River, NJ; said Mitchell and said Barnes assignors to General Foods Corporation, White Plains, N .Y., a corporation of Delaware No Drawing. Filed Sept. 4, 1963, Ser. No. 306,633 Claims. (Cl. 62-48) This invention relates to a technique for handling and transporting gas at atmospheric pressure in a limited volume. More specifically, it relates to a novel technique whereby large quantities of gas may be placed in a form suitable for handling at atmospheric pressure. This application is a continuation-in-part of application Serial No. 726,657, filed April 7, 1958, now US. Patent 2,975,- 603, and of application Serial No. 843,912, filed October 2, 1959, now US. Patent 3,086,370, and of application Serial No. 854,243, filed November 20, 1959, now abandoned.

As is well known to those skilled-in-the-art, large quantities of various gases are commonly handled, transported, and used in industry, in the laboratory, in hospitals, and in other places. Because of the physical properties of the gases, they are typically maintained and stored in thick-shelled containers under substantial pressure. This technique of handling gases is less than totally satisfactory for several reasons. The cost of manufacturing and, more importantly, the cost of handling the containers is excessive; in many cases the latter is disproportionately large in comparison to the value of the gas within the container. Furthermore, the necessity for storing the gas under high pressures requires use of specialized techniques.

In the case of carbon dioxide, for example, it is common to handle this gas in tank car quantities. Such a tank car may be designed to contain up to ten thousand gallons of material. Carbon dioxide could be maintained therein under high pressure in liquid phase, in which case the car might hold 35,000 pounds of gas at a typical pressure of 1000 p.s.i.g. (under these conditions, the temperature will be about 87 F.); the required thickness of steel plate required might be as much as one inch or more, typically 1.25 inches. Because of these limitations, it is more common to transport carbon dioxide in liquid phase at low pressures, i.e. typically about 300 to 350 p.s.i.g. In this case, the temperature would be maintained at about 5 F. to minus 5 F. or less. The car could then contain e.g. 76,000 pounds of carbon dioxide and the wall thickness required to sustain the pressure might be about inch.

Standard tank car of 10,000 gallons It is apparent from the above tabulation-summary that the pressures are high in either case and correspondingly the plate thickness required and the refrigeration required are all quite high. These factors all contribute to make the present techniques for handling this material in gas phase less than fully satisfactory.

It will also be apparent to those skilled-in-the-art that similar stringent conditions prevail for other modes of transporting and handling gases, e.g., tank trucks, moderate sized steel containers, etc., and also for other gases which may commonly be handled. However, despite the disadvantages of high costs, high pressures, required low temperatures and attendant refrigeration, and the high cost of the container arising from the great thickness of plate required, these techniques have heretofore been commonly employed because they were the best available; there has heretofore been no technique available for handling or transporting gases under mild conditions, i.e. primarily at low or atmospheric pressure, at: moderate temperature, and in thin-walled containers.

Carbon dioxide in particular may be handled in the form of Dry Ice; but unless this is done in well insulated or refrigerated cars, the losses will be high.

An important object of the present invention is to provide a simple, economical method of transporting a gas to a predetermined location, liberating the gas at the location, and then recovering the gas, either for immediate use or for later use.

According to one aspect of this invention, a conditionally stable hydrate forming gas may be transported under readily obtained conditions by the process which comprises maintaining a reservoir of an aqueous liquid, contacting the aqueous liquid with a conditionally stable hydrate forming gas under a pressure at least equal to the conditionally stable hydrate forming pressure, maintaining the aqueous liquid and the gas in contact for a time sufiicient to permit absorption in the liquid of gas in the form of a conditionally stable hydrate, maintaining the temperature of the liquid and the gas during absorption within the gasified-ice-freezing temperature range thereby forming gasified ice, transporting the gasified ice to a desired location of gas liberation, melting the ice at that location thereby liberating gas, and recovering the liberated gas.

In carrying out the process of this invention, it is preferred to use water as the aqueous liquid. Although some advantages in terms of reproducibility of precise conditions may be obtained by using distilled water, it is one of the features of this invention that ordinary tap water, well water, or water from any commercial or industrial source can be used without pretreatment. Under certain conditions it may be desirable to use water which may contain various ingredients and the terms water or aqueous liquid may be hereinafter employed to include Water containin g these materials as well as water, per se.

Under preferred conditions, the water may be placed within the desired container which is capable of withstanding the various temperatures and pressures prevailing during the course of the process. Gas in requisite amount, as hereinafter noted, is then admitted to the container. It may be possible to add the gas in solid or liquid form; under preferred conditions, it will be admitted in gaseous form.

The conditionally stable hydrate forming gases with which the techniques of this invention may be used include those gases which, under the conditions hereinafter set forth, form hydrates having the hereinafter designated properties. They are gases under atmospheric pressure; they have a boiling point below about 0 C.; and when combined with water in accordance with this invention, they give product hydrate-ices containing more than about 9 moles of water per mole of gas. These hydrates appear to be characterized by a loose bond between the gas and the water; gases which are tightly bound to the Water, cg. sulfur trioxide, do not form hydrates which '3: 2 may be used in practice of this invention. However, the solid hydrates, when prepared and stored under the conditions hereinafter noted, are stable for indefinite periods during which they retain their original physical and chemical properties. The hydrates may be decomposed by melting, e.g., by contact with a warm liquid.

Typical of the gases are various oxides of non-metals, typically nitrous oxide; sulfur-containing gases including hydrogen sulfide; chlorine-containing gases including chlorine or methyl chloride; helium and other inert gases, i.e., argon, krypton, neon, etc.; carbon monoxide; and carbon dioxide.

It will be apparent to those skilled-in-the-art that gases typified by fluorine which react with water to decompose the water are not included within the scope of this invention; nor are gases such as sulfur trioxide which form a hydrate having a very high degree of stability; nor are gases such as nitrogen, oxygen, or hydrogen which do not form unstable hydrates. Other examples will be apparent to those skilled-in-the-art.

Although it is not possible to state precisely why the herein noted unexpected and surprising results are obtained, it may be, particularly in the case of the preferred inorganic gases including e.g. nitrous oxide, carbon dioxide, carbon monoxide, helium, hydrogen sulfide, chlorine, etc., that some readily reversible reaction occurs between an inorganic portion of the molecule and the water with resulting formation of a compound; or it may be that the gas is held in a molecular dispersion within the crystal lattice of the ice that is formed.

When the reaction is conducted batchwise and the gas is to be added in gaseous form, the water will preferably be agitated and the gas under pressure will be admitted to the reaction chamber. Although the pressure may be varied depending upon the prevailing conditions and upon the gas, it will be above the conditionally stable-hydrateforming pressure.

It is a feature of this invention that the formation of the ice from the aqueous liquid and the conditionally stable hydrate forming gas may be effected either in the vessel in which it is to be transported or in an auxiliary reaction vessel. If the product ice is formed in the transporting vessel, then the amount of handling of the ice is reduced to a minimum. If the ice is formed under pressure in an auxiliary reaction vessel, then the transporting vessel can be operated under low pressure and be fabricated of thin walls. Preferably it will be formed in a vessel other than the transportation vessel; and this permits use of vessels which have thin walls and are therefore light in weight and less expensive to construct and transport.

The conditionally stable-hydrate-forming pressure of a particular gas may readily be determined by plotting the amount of gas retained in the frozen solid at various times at various pressures. At very low pressure, it will be noted that the amount of gas retained within the ice rapidly approaches a maximum or plateau (as the time of contact increases) at which point it remains regardless of how long the system is maintained under the constant pressure conditions of operation. If other runs are made wherein the pressure of operation is higher, a particular pressure (the conditionally stable-hydrate forming pressure) may be reached above which the amount of gas retained in the ice approaches a maximum or plateau, at which point it remains for a period of time which is less at higher pressure; and then the amount of gas increases substantially to a much higher level. This increase in quantity of gas retained in the solid signifies the formation of an unexpected hydrate. The so-formed hydrate is said to be conditionally stable because (a) it possesses a stability under the hereinafter defined conditions and (b) it may readily be decomposed by melting.

Although this conditionally stable-hydrate-forming pressure may vary for different gases, it may be of the order of 150-200 p.s.i.g.; when the gas is nitrous oxide, it appears to be about 150 p.s.i.g.; for carbon dioxide, it

4% appears to be about 200 p.s.i.g. The amount of gas entrapped or retained within the ice at this pressure may be called the minimum hydrate quantity of gas. A more preferred term is minimum hydrate ratio which will be employed to designate the number of milliliters of gas per gram of product ice.

The upper limit of pressure which should be employed at the end of the reaction will preferably be less than the vapor-liquid equilibrium pressure of the gas at the temperature of operation, under which condition there will be substantially no formation of liquefied gas within the system. When the gas employed is nitrous oxide, this pressure will be about 600 p.s.i.g.; when the gas is carbon dioxide, this pressure will be about 600 p.s.i.g. Other gases may have higher or lower vapor-liquid equilibrium pressure at the temperature of operation; but generally, 600 p.s.i.g. may represent a maximum pressure below which it is preferred to operate in accordance with this invention.

It is possible in accordance with prior art techniques, to incorporate small amounts of gas, e.g., carbon dioxide, into water at low pressures and to freeze the resulting mixture to give an ice containing small quantities of gas. For example, if the gas be carbon dioxide and the pressure be 50 p.s.i.g., the volume of carbon dioxide enclosed within the ice in the prior art technique may be only of the order of about 4-5 milliliters of gas per gram of ice; if the pressure be increased to, e.g., 70 p.s.i.g., the gas content is raised to, e.g., about 8; even if the pressure be increased to about 150 p.s.i.g., the gas content is only increased to about 1415.

The present invention utilizes the fact that use of gas pressures above the hydrate forming pressure of approximately 150-200 p.s.i.g. permits attainment of ice containing an unexpectedly large gas content. Below this pressure, the maximum ratio appears to be below 19 in the case of carbon dioxide; and in the case of, e.g., nitrous oxide, the ratio appears to be below 15 As higher pressures are used, up to about 600 p.s.i.g., it is possible to increase the amount of gas in the product ice after a particular time, or alternatively to obtain in a shorter time, much greater amounts up to a level of about 120 milliliters of gas in the case of carbon dioxide per gram of ice. Preferably, the pressure of operation will be 200400 p.s.i.g.

The temperature of the aqueous liquid during pressuri- Zation thereof with gas should be (a) above the freezing point of that liquid under the prevailing pressure, i.e., above about 0 C. when pure water is employed; and pref erably (b) slightly below the freezing point of the product ice under the conditions of operation. The temperature of the system during the reaction, as above-defined, wilt be referred to as the gasified-ice-freezing range and wilt encompass the range from about 0 C. up to the freezing point of the gasified ice which may be as high as 14 C. or more. The reaction mixture may be maintained by appropriate means, e.g., by immersion in a bath or by circulation of refrigerant through the reaction vessel, at the desired temperature. As the gas is absorbed into the agitated liquid, more gas may be admitted to the system to maintain gas pressure at the desired level within the preferred limits of 150 p.s.i.g. or 200 p.s.i.g. up to 600 p.s.i.g. Preferably the gas pressure will be maintained constant during the course of the reaction.

The time of contact of the liquid and the gas and the other conditions noted may vary somewhat depending on the particular characteristics of the system in which the reaction is carried out. Typically, however, the time of reaction will be controlled to give the desired amount of gas in the product varying from, in the case of carbon dioxide, 25 ml. to about 100 ml. per gram of ice, and in the case of nitrous oxide 15 ml. to about 100 ml. per gram of ice. It will be preferably controlled to give about 5090 ml. per gram for carbon dioxide and 4055 for nitrous oxide.

At the end of the desired time, the so-prepared ice coni tains the desired gas in large quantities and the ice is ready to be used for transportation of the gas. If the ice has been prepared in an auxiliary reaction vessel, as in the preferred embodiment, it may be broken up and conveyed to the vessel in which it is to be transported. If the ice has been prepared in the transportation vessel, it may be used as is.

In either alternative, however, and especially when the ice has been prepared at pressures above about 4-00 p.s.i.g., it is preferred that it be degassed or stabilized for about 24 hours at about minus C. During this period, any gas which may loosely be held within the product is evolved. Liquefied gas, which may be within the mass, volatizes and passes otf from the solid product during this degassing period.

The various analytical techniques for determining the amount of gas within the product ice, etc. are preferably conducted on this degassed or stabilized product.

The degassed material is highly stable with respect to its ability to retain its constant composition and it is resistant to shock.

The freezing points of the gasified ices prepared in accordance with this invention are all above 0 C. and may be as high as 14 C. or more under pressure. In this respect, they differ from ices containing lesser amounts of gas and from ices prepared at pressure below these prescribed for the process of this invention. Ices prepared at pressures less than about 150-200 p.s.i.g. and/or containing less than the indicated minimum of gas per gram of ice, have melting points which are at or below 0 C.

There is a further indication of discontinuity which may indicate that there is unexpected compound formation or some unusual bonding force other than more physical entrapment of the gas by the ice when the process is carried out above the minimum pressure noted. It has been found, for example, in the case of nitrous oxide that it is not possible to prepare a gasilied ice containing a higher ratio of gas to solid than about 15 ml. of gas per gram of product ice when the pressure of operation is less than about 150 p.s.i.g. For example, if the process is conducted at 50 p.s.i.g., a maxi-mum ratio of about 3 is obtained after about 45 minutes and the ratio is maintained at about this level regardless of how much longer the pressurization is conducted. if the pressure be about 100 p.s.i.g., the asymtotic maximum, also reached after about 30 minutes, is about 7.

It thus appears that under the particular conditions of operation prescribed for this process that the gas, e.g., nitrous oxide, retained in the product in ratios greater than the indicated minimum, e.g., 15, is present in some unusual or unexpected form. The term bound gas may be used to describe the gas and specifically it refers to the gas which, in amount greater than the indicated minimum, is not vaporized from the gasified ice when the latter is stabilized at 10 C. for 24 hours and which, in View of the above-noted anomolous behavior, appears to be present in a characteristic but unexpected manner.

As the pressure is increased above 125l50 p.s.i.g. in the case of nitrous oxide, the plots of gas within the ice as a function of time of contact, generally quickly reach a plateau at or substantially above about 15, remain at this plateau for a brief period of time which is less at higher pressures, and then rise higher, the height generally increasing as the pressure increases. For example, in one series of runs, the gas enclosed at 50, 100, 150, 200, 300, and 400 p.s.i.g. was about 3, 7, 15, 57, 60 and 80 ml. of gas p r gram of ice, respectively, after 90 minutes of stirring at a temperature of 0 C. It is possible, by operating at different pressures within the limits herein noted, to obtain the same level of gas enclosure by varying the time.

The upper limit of the range of pressures which can be employed, for all practical purposes, will be about 600 p.s.i.g. More specifically, it is found that the product gasified ice is more stable when the pressure of the gas is correlated with the temperature of the water-gas mixture so that the pressure is less than the liquid-vapor equilibrium pressure of the gas at that temperature.

The gasified ice which may be used to transport gas in accordance with this invention, resembles ordinary ice. It may be cloudy or clear in appearance, and may be free of liquid. It is a particular feature of this invention that when prepared according to the preferred technique, the ice has a freezing point under pressure substantially above 0 C., i.e., it may be as high as 14 C. or more. Most commonly, it will be about 4 C.8 C. A characteristic feature of the gasified ice product is its ability to release gas at a controllable rate when melted as, e.g., by adding the ice to an aqueous liquid.

The novel gasified ice, an ice containing bound gas, comprises a solid matrix of ice containing a conditionally stable hydrate forming gas at a partial pressure at least as great as the conditionally stable hydrate forming pressure and less than the vapor-liquid equilibrium pressure at the temperature of formation and in amount at least equal to the minimum hydrate quantity of gas.

The density of the product in the case of carbon dioxide may be of the order of 0.940.99 gm. per cc. or higher which is heavier than ordinary ice, which has a density of about 0.92 gm. per cc.

The stability of the novel product of this invention is good below about 0 C. Its initial stability is favorable in that any gas which is not securely locked within the ice matrix is readily liberated during the degassing or stabilizing period without danger of explosion or product deterioration. After this degassing, the stabilized product has a shelf life which is at least 30 days, and usually substantially longer, when the ice is maintained under controlled conditions of temperature. It is stable for an extended time under normal freezing conditions in a freezer, i.e. at minus 10 C.

In the case of a gasified ice containing nitrous oxide, the minimum hydrate ratio is of the order of about 15 ml. of gas per gram of product ice, which is obtained at about 150 p.s.i.g. Although it is readily possible, in the case of nitrous oxide, to attain ratios as high as l00 at pressures of 500600 p.s.i.g., the ratio in the preferred product may be 50'75 conveniently attained at 200-400 p.s.i.g.

In the case of carbon dioxide, the novel gasified ice of this invention preferably contains at least about 25 milliliters of gas per gram of ice, which is roughly equivalent to 25 volumes of gas per volume of ice. Although it is readily possible to produce carbonated ice containing ratios of gas to solid as high as -415 to 1, the preferred product of this invention will contain a ratio of 50-90 to 1 and this will conveniently be prepared at 300 400 p.s.i.g. It is found that such a product, i.e. one containing a ratio of 5090 to 1 is characterized by its high stability.

The so-prepared stable product is transported (including storage at the point of manufacture and/ or use) without danger of loss of gas or explosion. If it has been prepared in an auxiliary reaction vessel, it may be broken up and conveyed to the transporting or storage tankjust as ordinary chopped ice is handled. It may be maintained in the tank under any refrigeration conditions which provide a temperature below the freezing point of typically 4-8 C. of the ice.

A typical tank car of 10,000 gallons capacity when used to store carbon dioxide in accordance with this invention could have the following characteristics, when full loaded:

Content (lbs.) 10,300 Typical storage pressure, (p.s.i.g.) *0

Typical temp. C) l0 Plate thickness Refrigeration reqd, (Btu/hr.) 4 Cost of container-material percent 5 *Atm. presure. With bracing.

It will be apparent to those skilled-in-the-art that the product of this invention may be stored and transported at atmospheric pressure in thin-walled vessels; and that the only limitation on the wall thickness is that it be sufficiently strong to support the weight of the material.

The so-prepared ice containing the desired gas may be stored indefinitely. When it is desired to liberate the stored gas, this can be efiected by melting the ice. Commonly this can be done by adding warm water to the tank car or preferably by passing warm water or steam through coils in the car. The rate and amount of gas liberated may be controlled by regulating the quantity of heat added.

After liberation, the gas released is recovered, either for immediate use or for temporary storage as a gas for utilization at a later time. Such recovery of liberated gas is a factor that characterizes the present inventive method from a process in which a gas in bound hydrate form is released and then permitted to be dissipated without segregation of the liberated gas for immediate or subsequent use. By the term, recovery, is specifically meant the reclamation and segregation of the gas liberated and its restriction in a chamber in a substantially pure form suitable for one or more uses.

According to a specific example of this invention, Water at 25 C. was placed in a pressure vessel, which was then closed. Agitation was started, and nitrous oxide was admitted thereto at 400 p.s.i.g. The vessel was cooled by a constant low temperature liquid refrigerant which maintained the contents at just slightly above C. The nitrous oxide feed was adjusted to keep the pressure at 400 p.s.i.g. during the course of the reaction. After 120 minutes, the vessel was cooled, further depressurized, and opened. The contents were removed and the ice was maintained for 24 hours at minus 10 C. to effect removal of non-bound gas. Testing of the degasified product revealed that it had a nitrous oxide content of 93 volume of nitrous oxide per gram of ice.

This material was placed in bags and stored at minus 10 C. for 33 days. At the end of this time, the material was tested and its gas content was found to be the same as that at the beginning of the test.

Gas was liberated from the so-stored product by addition thereto of C. water, the rate of gas liberation being easily controlled by controlling the rate of flow of the water to the ice. The liberated gas was recovered for use as an anesthetic.

According to another specific example of this invention, a 10,000 gallon tank car containing 7,000 gallons of water at C. may be closed and nitrous oxide admitted thereto at 300 p.s.i.g. The vessel is cooled by refrigeration coils containing refrigerant which will maintain the contents at just slightly above 0 C. Agitation may be provided. The nitrous oxide feed is adjusted to keep the pressure at 300 p.s.i.g. during the course of the reaction. After minutes, the vessel may be cooled to minus 10 C., depressurized, and opened. The solid ice contents are maintained for 24 hours at minus 10 C. to eifect removal of non-bound gas. Testing of the degasified product reveals that it had a nitrous oxide content of 57 volumes of nitrous oxide per volume of product ice.

A sample of the gasified ice, if subjected to storage tests at minus 10 C., may show that no loss of gas is apparent during 33 days.

Release of the gas from the tank car can be effected by passing warm water, preferably at 20 C.25 C. through the coils in the tank car. The gas can be liberated in controllable manner and recovered.

According to still another specific example of this invention, water at 25 C. was placed within a pressure vessel which was closed, agitation started, and carbon dioxide was admitted thereto at 400 p.s.i.g. The vessel was cooled to a constant temperature which maintained the contents at just slightly over 0 C. The carbon dioxide feed was adjusted to keep the pressure at 400 p.s.i.g. during the course of the reaction. After minutes, the vessel was cooled to about minus 10 C., depressurized and opened. The contents were removed and the solid ice was stored for 24 hours at 10 C. to effect stabilization. Testing of the degasified product revealed that it had a carbon dioxide content of 70 volumes of carbon dioxide per gram of ice.

The degasified carbonated ice in superficial appearance resembled ordinary ice. It had a density of about 0.97

gm. per cc.

A sample of the carbonated ice was subjected to storage tests in a refrigerator at 10 C. It was tested after 33 days and no loss of carbon dioxide gas was apparent.

This gasified ice which had been stored was placed in a gas-tight container. Gas was liberated therefrom by addition of controlled quantities of warm (20 C.25 C.) water, the liberated gas being recovered and used immediately in the packing of roasted and ground coffee.

The advantages of the instant invention will be readily apparent to those skilled in this art. It permits handling of large quantities of gases at atmospheric pressure under conditions such that no special techniques are required. The technique is such that controlled amounts of gas may be liberated and recovered as desired and with minimum danger of explosion, etc.

It will be apparent to those skilled-in-the-art that although the instant invention has been described in connection with several specific examples, there will be numerous modifications which may be made which fall within the scope of this invention.

What is claimed is:

1. The method of transporting a conditionally stable hydrate-forming gas, which comprises maintaining a reservoir of an aqueous liquid, contacting the aqueous liquid with a conditionally stable hydrate-forming gas under a pressure of from about p.s.i.g. to about 600 p.s.i.g., maintaining the aqueous liquid and the gas in contact for a time sufficient to permit absorption of the gas in the liquid in the form of a conditionally stable hydrate, maintaining the temperature of the liquid and the gas during said absorption within the gasified ice-freezing temperature range of from about 0 C. to about 14 C. thereby forming gasified ice, transporting the thus formed gasified ice to a desired point of gas liberation under atmospheric pressure while maintaining it at a temperature below its melting point, melting the ice at said point to liberate the gas, and recovering the liberated gas.

2. The method of transporting a conditionally stable hydrate-forming gas selected from the group consisting of carbon dioxide, nitrous oxide, hydrogen sulfide, chlorine, methyl chloride, carbon monoxide, and inert gases, which comprises maintaining a reservoir of an aqueous liquid, contacting the aqueous liquid with a conditionally stable hydrate-forming gas under a pressure of from about 150 p.s.i.g. to about 600 p.s.i.g., maintaining the aqueous liquid and the gas in contact for a time sufiicient to permit absorption of the gas in the liquid in the form of a conditionally stable hydrate, maintaining the temperature of the liquid and the gas during said absorption within the gasified ice-freezing temperature range thereby forming gasified ice, transporting the thus formed gasified ice in a vessel to a desired point of gas liberation under atmospheric pressure while maintaining the gasified ice at a temperature below its melting point, melting the ice at said point to liberate the gas, and recovering the liberated gas.

3. The method claimed in claim 2, in which the reservoir in which the aqueous liquid is maintained is the transporting vessel.

4. The method claimed in claim 2, in which the gasi fied ice is broken up prior to being transported to the point of gas liberation.

5. A method according to claim 1 in which after being 9 10 formed the gasified ice is permitted to stand for about 24 2,575,509 11/1951 Bayston 62-1 hours to stabilize the ice. 2,590,542 3/1952 Jones 62-1 2,683,651 7/1954 Williamson et al 252-67 References Cited by the Examiner 2,904,511 9/1959 D h 62 1 UNITED STATES PATENTS 5 3,086,370 4/ 1963 Barnes et a1 621 2,217,678 10/1940 Goosmann 62-1 2 240 7 9 5 941 Glazer 2 ROBERT A. OLEARY, Primary Examiner. 

1. THE METHOD OF TRANSPORTING A CONDITIONALLY STABLE HYDRATE-FORMING GAS, WHICH COMPRISES MAINTAINING A RESERVOIR OF AN AQUEOUS LIQUID, CONTACTING THE AQUEOUS LIQUID WITH A CONDITIONALLY STABLE HYDRATE-FORMING GAS UNDER A PRESSURE OF FROM ABOUT 150 P.S.I.G. TO ABOUT 600 P.S.I.G., MAINTAINING THE AQUEOUS LIQUID AND THE GS IN CONTACT FOR A TIME SUFFICIENT TO PERMIT ABSORPTION OF THE GAS IN THE LIQUID IN THE FORM OF A CONDITIONALLY STABLE HYDRATE, MAINTAINING THE TEMPERATURE OF THE LIQUID AND THE GAS DURING SAID ABSORPITON WITHIN THE GASIFIED ICE-FREEZING TEMPERATURE RANGE OF FROM ABOUT 0*C. TO ABOUT 14*C. THEREBY FORMING GASIFIED ICE, TRANSPORTING THE THUS FORMED GASIFIED ICE TO DESIRED POINT OF GAS LIBERATION UNDER ATMOSPHERIC PRESSURE WHILE MAINTAINING IT AT A TEMPERATURE BELOW ITS MELTING POINT, MELTING THE ICE AT SAID POINT TO LIBERATE THE GAS, AND RECOVERING THE LIBERATED GAS. 